<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title> New Document</title>
 </head>
 <body>
<script type ="text/javascript">
//function add(x,y){return x+y;}
var num1="89784sdf";
//alert(add.valueOf());
//var ret ="";
//ret=escape("ssssdffgghha中国1111236");
//document.write(ret);
//eval("var detetime=new Date();document.write(detetime);")
alert(isNaN(num1));
/*
if(num1.constructor==String)
alert(num1.constructor);
else if(num1.constructor==Number)
alert("这是个number类型");
else if(num1.constructor==Function)
alert("这是个Function类型");
*/
</script>
<sup>上标</sup>
 </body>
 </html>